The invention relates to a constant velocity joint having an outer joint part, an inner joint part and torque transmitting elements which, in the direction of rotation, constitute positive engaging means between the outer joint part and the inner joint part. The outer joint part comprises means for threading the positive engaging means to a shaft attachment flange, which threading means are positioned at the circumference on a diameter outside the rolling circle of the torque transmitting elements.
The invention also relates to an assembly consisting of a constant velocity universal joint having an outer joint part, an inner joint part and torque transmitting elements which, in the direction of rotation, constitute positive engaging means between the outer joint part and the inner joint part and a shaft attachment flange. Not the joint but the assembly includes a shaft attachment flange. Both the outer joint part and the shaft attachment flange comprising threaded connecting means for the purpose of being threaded to one another. The threaded connecting means are positioned at the circumference on a diameter outside a rolling circle of the torque transmitting elements. Also, there is provided centering means for centering the outer joint part relative to the shaft attachment flange.
The constant velocity joints mentioned here include all joint types provided for being threaded on, i.e., fixed joints and plunging joints. Both categories include universal ball joints, with the torque transmitting means constituting balls which run in outer ball grooves and inner ball grooves which are held by a ball cage in a common plane, as well as tripod joints wherein the torque transmitting elements are tripod rollers which are held on tripod arms of an inner joint part and roll in tracks of the outer joint part.
To the extent that reference is made to a rolling circle diameter, the latter, in constant velocity ball joints, is the diameter of the circle through the ball centers when the joint is in the aligned position. In the case of tripod joints, the rolling circle diameter is the diameter of the circle through the roller points of contact with the tracks when the joint is in the aligned position.
In the present case, said shaft attachment flange is always slipped onto an output shaft of a gearbox. Said gearbox can be a manual or an automatic gearbox, with the gearbox output shaft then being connected by means of the constant velocity joint in question to a propeller shaft or cardan shaft in the widest sense. Instead of a gearbox, it is also possible to use a differential drive, in which case the respective differential output shaft is coupled by the constant velocity joint in question to a side shaft leading to the driving wheels.
The shafts connected by said joints to the gearbox output flanges are balanced prior to being fitted in the vehicle because any out-of-balance can be transferred in the form of vibrations to the vehicle and, thus, has to be avoided. When fitting the shafts via the threading means of the constant velocity joint to a gearbox output flange, inadequate centering can again lead to out-of-balance. This adversely affects the noise behavior and the driving comfort, because after completion of the assembly operation, the vehicle, as a rule, does not undergo any further balancing operations. Normally, the centering means are provided at the outer joint part and at the flange on the outer diameter of the outer part. However, centering of the gearbox output flange relative to a gearbox output shaft takes place in the region of the shaft splines of a splined sleeve at the flange on the one hand and of a splined portion at the free shaft end of the gearbox output shaft on the other hand. The accurately executed centering measures carried out between the flange and the outer joint part are nullified by the possible axis offset of the flange relative to the gearbox output shaft. This offset may occur in the region of the shaft splines.
It has already been attempted to use an additional centering element between the outer joint part and the gearbox output shaft which, as a formed sheet metal part, is centered on the outer diameter of the outer joint part on the one hand and on the extended shaft end of the gearbox output shaft on the other hand. In this case, the insufficiently centered shaft flange can only contribute by means of its own mass to a small amount of out-of-balance, whereas the well-balanced shaft is well-centered by the sheet-metal-cover-like centering element relative to the gearbox output shaft. However, the disadvantage is that the tolerances or centering errors between the gearbox output shaft and the centering element on the one hand, and between the centering element and the outer joint part on the other hand are added up, so that, in total, there occurs a considerable axis offset of the shaft connected by the joint relative to the gearbox output shaft. This axis offset leads to a considerable amount of out-of-balance. In addition, said sheet metal element is relatively soft so that, when the threading means between the flange and outer joint part are tightened, the threading means can possibly be distorted. Finally, the centering elements produced so far comprise a central opening, so that an additional transport cover has to be provided to seal the joint during transport.